package com.shenming.sms.util;

/*
 * To change the template for this generated file go to
 * Window&gt;Preferences&gt;Java&gt;Code Generation&gt;Code and Comments
 */
import java.io.*;

/**
 * A class to encode Base64 streams and strings.
 * See RFC 1521 section 5.2 for details of the Base64 algorithm.
 * <p>
 * This class can be used for encoding strings:
 * <blockquote><pre>
 * String unencoded = "webmaster:try2gueSS";
 * String encoded = Base64Encoder.encode(unencoded);
 * </pre></blockquote>
 * or for encoding streams:
 * <blockquote><pre>
 * OutputStream out = new Base64Encoder(System.out);
 * </pre></blockquote>
 *
 */
public class Base64Encoder extends FilterOutputStream {

	private static final char[] chars = {
		'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J',
		'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T',
		'U', 'V', 'W', 'X', 'Y', 'Z', 'a', 'b', 'c', 'd',
		'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n',
		'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x',
		'y', 'z', '0', '1', '2', '3', '4', '5', '6', '7',
		'8', '9', '+', '/'
	};

	private int charCount;
	private int carryOver;

	/**
	 * Constructs a new Base64 encoder that writes output to the given
	 * OutputStream.
	 *
	 * @param out the output stream
	 */
	public Base64Encoder(OutputStream out) {
		super(out);
	}

	/**
	 * Writes the given byte to the output stream in an encoded form.
	 *
	 * @exception IOException if an I/O error occurs
	 */
	public void write(int b) throws IOException {
		// Take 24-bits from three octets, translate into four encoded chars
		// Break lines at 76 chars
		// If necessary, pad with 0 bits on the right at the end
		// Use = signs as padding at the end to ensure encodedLength % 4 == 0

		// Remove the sign bit,
		// thanks to Christian Schweingruber <chrigu@lorraine.ch>
		if (b < 0) {
			b += 256;
		}

		// First byte use first six bits, save last two bits
		if (charCount % 3 == 0) {
			int lookup = b >> 2;
			carryOver = b & 3;        // last two bits
			out.write(chars[lookup]);
		}
		// Second byte use previous two bits and first four new bits,
		// save last four bits
		else if (charCount % 3 == 1) {
			int lookup = ((carryOver << 4) + (b >> 4)) & 63;
			carryOver = b & 15;       // last four bits
			out.write(chars[lookup]);
		}
		// Third byte use previous four bits and first two new bits,
		// then use last six new bits
		else if (charCount % 3 == 2) {
			int lookup = ((carryOver << 2) + (b >> 6)) & 63;
			out.write(chars[lookup]);
			lookup = b & 63;          // last six bits
			out.write(chars[lookup]);
			carryOver = 0;
		}
		charCount++;

		// Add newline every 76 output chars (that's 57 input chars)
		if (charCount % 57 == 0) {
			out.write('\n');
		}
	}

	/**
	 * Writes the given byte array to the output stream in an
	 * encoded form.
	 *
	 * @param b the data to be written
	 * @param off the start offset of the data
	 * @param len the length of the data
	 * @exception IOException if an I/O error occurs
	 */
	public void write(byte[] b, int off, int len) throws IOException {
		// This could of course be optimized
		for (int i = 0; i < len; i++) {
			write(b[off + i]);
		}
	}

	/**
	 * Closes the stream, this MUST be called to ensure proper padding is
	 * written to the end of the output stream.
	 *
	 * @exception IOException if an I/O error occurs
	 */
	public void close() throws IOException {
		// Handle leftover bytes
		if (charCount % 3 == 1) {  // one leftover
			int lookup = (carryOver << 4) & 63;
			out.write(chars[lookup]);
			out.write('=');
			out.write('=');
		}
		else if (charCount % 3 == 2) {  // two leftovers
			int lookup = (carryOver << 2) & 63;
			out.write(chars[lookup]);
			out.write('=');
		}
		super.close();
	}

	/**
	 * Returns the encoded form of the given unencoded string.
	 *
	 * @param unencoded the string to encode
	 * @return the encoded form of the unencoded string
	 */
	public static String encode(String unencoded) {
		ByteArrayOutputStream out =
			new ByteArrayOutputStream((int) (unencoded.length() * 1.37));
		Base64Encoder encodedOut = new Base64Encoder(out);

		byte[] bytes = null;
		try {
			bytes = unencoded.getBytes("8859_1");
		}
		catch (UnsupportedEncodingException ignored) { }

		try {
			encodedOut.write(bytes);
			encodedOut.close();

			return out.toString("8859_1");
		}
		catch (IOException ignored) { return null; }
	}

	/**
	 * Returns the encoded form of the given unencoded byte array.
	 *
	 * @param unencoded the byte array to encode
	 * @return the encoded form of the unencoded string
	 */
	public static String encodeBytes(byte[] unencoded) {
		ByteArrayOutputStream out =
			new ByteArrayOutputStream((int) (unencoded.length * 1.37));
		Base64Encoder encodedOut = new Base64Encoder(out);

		try {
			encodedOut.write(unencoded);
			encodedOut.close();

			return out.toString("8859_1");
		}
		catch (IOException ignored) { return null; }
	}
}

